1. Field of the Invention
The present invention relates to an organic-light-emitting-diode (OLED) flat-panel light-source apparatus and, more particularly, to an OLED flat-panel light-source apparatus and a method of manufacturing the same, which may improve the uniformity of electrical and optical properties of a large-area OLED flat-panel light-source apparatus required for an illumination system and a display device.
2. Discussion of Related Art
An organic light emitting diode (OLED) flat-panel light-source technique may be applied in various fields including an energy-saving eco-friendly illumination system, a flexible display device, a medical illumination system, and a backlight unit (BLU) of an LCD display device.
FIGS. 1 and 2 are a cross-sectional view and plan view, respectively, of a conventional OLED flat-panel light-source apparatus.
Referring to FIGS. 1 and 2, the conventional OLED flat-panel light-source apparatus may include a substrate 110, an anode 120, an organic emission layer (EML) 130, and a cathode 140.
The organic EML 130 may be interposed between the anode 120 and the cathode 140, each of which may be formed of a transparent metal layer or a reflective metal layer. When power is applied between the anode 120 and the cathode 140, the organic EML 130 may emit light.
However, the conventional OLED flat-panel light-source apparatus should supply current to the organic EML 130 through the anode 120 and the cathode 140 so that the organic EML 130 can emit light. In this case, IR-drop may occur due to resistance components of the anode 120 and the cathode 140. Thus, the conventional OLED flat-panel light-source apparatus may have non-uniform electrical and optical properties according to a position of an emission region due to the IR-drop. Also, in the conventional OLED flat-panel light-source apparatus, the emission region may be increased due to the scaling-up of OLED flat-panel light-surface apparatuses, thus increasing the non-uniformity of the electrical and optical properties.
In order to overcome the above-described drawbacks, an OLED flat-panel light-source apparatus using a subsidiary electrode layer has lately been proposed to reduce a sheet resistance component of an electrode and the non-uniformity of the electrical and optical properties due to the IR-drop.
FIGS. 3 through 6 are diagrams of an OLED flat-panel light-source apparatus including a subsidiary electrode layer. Specifically, FIGS. 3 and 4 are a cross-sectional view and plan view, respectively, of an OLED flat-panel light-source apparatus in which a subsidiary electrode is formed between an anode and an organic material, and FIGS. 5 and 6 are a cross-sectional view and plan view, respectively, of an OLED flat-panel light-source apparatus in which a subsidiary electrode is formed between an anode and a substrate.
Referring to FIGS. 3 through 6, the OLED flat-panel light-source apparatus may include a substrate 310, an anode 320, an organic EML 330, a cathode 340, and a subsidiary electrode layer. Here, the subsidiary electrode layer may include a plurality of subsidiary electrodes 350 and an insulating layer 354 configured to compensate the coverage of the plurality of subsidiary electrodes 350.
Each of the subsidiary electrodes 350 may include a metal layer 352 having a low sheet resistance. Thus, the plurality of subsidiary electrodes 350 may reduce a sheet-resistance component of the anode 320 or the cathode 340, thereby reducing non-uniformity due to IR-drop.
However, it is difficult to embody a large-area OLED flat-panel light-source apparatus having uniform electrical and optical properties using a conventional method of manufacturing a large-area OLED flat-panel light-source apparatus.